Spoilers ahead for Episode 7 of Chicago Fire Season 8, called "Welcome To Crazytown."
Chicago Fire got appropriately crazy with "Welcome To Crazytown" for many reasons, but primarily due to the change that has taken Kelly Severide out of Firehouse 51, and Squad 8 is presumably without a leader until 51 finds a way to fill the Severide void. While the evidence has been mounting up that Severide might not be around the firehouse moving forward in Season 8, fans probably didn't see the twist going down the way it did, and the question now is: how long is it going to last?
Severide's penchant for helping out the Office of Fire Investigation in cases of suspected arson led to OFI seriously courting him to leave Squad and join them in their investigations. While Severide has always been happy to go rogue and help OFI and/or investigate potential arson without OFI, he wasn't tempted even a little bit to give up his place at Firehouse 51.
OFI seemed to be crossing lines to try and poach him, as a transfer order was put in without Severide's consent. This led to the reveal that it wasn't somebody at OFI who was trying to force Severide's hand, but rather Commissioner Grissom.
Severide wasn't inclined to listen to anything Grissom had to say unless it was that Severide could return to work as usual at 51, but he managed to bring Severide around by telling him that public service is supposed to be about sacrificing to help people rather than pursuing personal goals.
Grissom then amended his request to simply asking Severide to help OFI clear their backlog of cases, and if he wanted to return to Firehouse 51 afterward, he could. So, "Welcome To Crazytown" established the vague potential end date of Severide's time at OFI: whenever the backlog is less backed up. Courtesy of Chicago Fire showrunner Derek Haas via Twitter, it's probably safe to say that Severide will still be helping OFI for at least another few episodes.
This tweet, which went up before Season 8 even launched, technically isn't phrased in a way that 100% rules out Severide returning before the winter break or a twist that has Severide coming back and Casey leaving. After all, Derek Haas, who also shared with CinemaBlend why Otis' death was so gruesome, could have had some tricks up his sleeve if he was going to shoot this out online months before the winter finale would air.
Still, I think we should count on Severide being on OFI detail into at least early 2020, and possibly well into the second half of the season. Not only has Firehouse 51 lost Otis as a member of the team, but now Severide won't be leading Squad!
See what happens next in new episodes of Chicago Fire airing Wednesdays at 9 p.m. ET on NBC, between new episodes of Chicago Med at 8 p.m. ET and Chicago P.D. at 10 p.m. ET.